Well, I drove this before with my neices and since I was much younger and they weren't my kids-my opinion might not be too helpful. I am now a mom to a toddler, and I do admire your willingness to drive. How old are your kids?
When we went we stopped in Chatanooga TN and stayed at the Chatanooga Choo Choo Hotel (back then it was a Holiday Inn..who knows now) . It was pretty neat and the kids had fun there. It was a good break for all of us. The kids swam, burned off energy, we took showers, had a nice meal and then got on the road again quickly the next morning.
I am sure you will be getting a VCR or DVD for the vehicle--that really helps. You can get on NetFlix.com and rent them for a long period of time. Better than late fees at Blockbuster.
You gotta love the Suburban--we only have one child and I drive a Yukon Denali. We have plenty of room, my husband still has trouble justifying that purchase as well. We are flying in October to Disney and got fares for $144 pp roundtrip/non-stop. I know we would spend that each way on gas in my vehicle!! Have a safe trip and best of luck!!